Elsevier

Gait & Posture

Volume 32, Issue 4, October 2010, Pages 664-666
Gait & Posture

Short communication
Footscan pressure insoles: Accuracy and reliability of force and pressure measurements in running

https://doi.org/10.1016/j.gaitpost.2010.08.002Get rights and content

Abstract

In the current investigation, the accuracy and reliability of two pairs of Footscan pressure insoles (500 Hz, RSscan, Belgium) was assessed, with four female (pair 1) and four male (pair 2) participants each performing 16 running trials (3.8 m/s ± 5%). Intraclass Correlation Coefficients (ICC) revealed that the reliability of the force and pressure data was generally excellent (ICC > 0.75). In comparison with impact and propulsive force data collected simultaneously with a force plate (AMTI, 500 Hz), insole data were significantly lower (p < 0.05). Therefore, despite the excellent reliability of measurements, the accuracy of the impact and propulsive forces taken with the Footscan pressure insole is low. It is concluded that data collected without appropriate calibration should be used with caution, particularly if the aim is to use the data for a comparison of absolute force and pressure magnitudes with criterion values.

Introduction

Advancements in microcomputer technology have enabled manufacturers to develop in-shoe devices that provide measurements of plantar forces and pressures at the shoe-foot interface [1]. Like many brands of pressure insole, the Footscan® system is constructed with evenly distributed sensor cells. Each cell consists of a piezo-electric crystal and is an independent force measuring device. The sum of this force is equivalent to the total force applied to the body [2] and should equal the vertical force vector if measured simultaneously with a force plate. Because of the cell measurement of force, this technology can calculate plantar pressure based on the measured vertical load and the cell area [3]. For pressure insoles to be used a realistic and reliable measurement of plantar forces and pressures should be provided, yet despite its use in research [4], the accuracy and reliability of this system is not known. This investigation aims to provide this information.

Section snippets

Method

Four female (23.5 ± 2.5 yr, 72.0 ± 2.2 kg) and four male (24.5 ± 1 yr, 87.3 ± 2.3 kg) participants were recruited to test two pairs of pressure insoles (females wore pair 1, sizes UK5-6; males wore pair 2, sizes UK9-10) (RSscan International, Belgium, 500 Hz). In-shoe temperature was measured at a consistent 36.5 °C throughout all trials.

Participants performed 16 running trials (3.81 m/s ± 5%). For each acceptable trial, participants contacted a force plate (AMTI, 500 Hz) without adjusting their normal gait, so

Results

When the data from each insole and participant were combined, ICC coefficients were 0.75 or greater. ICC values of 0.5–0.74 were also observed for much of the data when separated into the insole pairs and when the data for each pair were separated into the left and right insole. Peak pressure measurements at metatarsal one and three (right insole of pair 1), metatarsal two (left insole of pair 2 and pair 2 combined) and peak impact force (left insole of pair 2), was less than 0.5 (Table 1).

The

Discussion

In comparison to published standards (r > 0.75) [5], the combined data from the left and right step from two different pairs of insoles indicated excellent reliability for all measured parameters. Good to excellent reliability was generally observed for both pairs of insoles and for both the left and right insole in each pair, yet for selected single insoles and anatomical areas, poor reliability was observed. This has also been shown previously although not at the same locations as those in the

Conflict of interest statement

There is no conflict of interest with any other parties.

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